The present invention relates to a device to facilitate the servicing of oil well rod pumps.
A conventional oil well pump used in pumping oil from an operating well consists primarily of a horizontal main beam or shaft which pivots in the center (like a teeter totter) with one end of the main beam being driven up and down by a motor. The other end of the main beam, or "head", has attached to it a steel rod known as a "polish rod" which is moved up and down in the valve mechanism of the oil well by the head of the main beam moving through an arc of approximately 10 feet on each reciprocation of the main beam.
At its lower end, the polish rod is restrained from moving too deeply into the well head by a collar-type clamp. At its upper end, the polish rod is attached to the head of the main beam by a hinged, U-shaped bridle and by a second clamp. The bridle allows the polish rod to constantly remain in a vertical position while it is moved up and down in the oil well valve mechanism.
In order to service the bridle, rod or motor powering the beam, it is essential that the weight of the rod string be supported. Conventionally, it is supported by moving the clamps on the bridle and the lower end of the polish rod so that the lower clamp ultimately rests on the oil well valve, thereby supporting the entire weight of the rod string. This creates problems since the surface of the polish rod must be kept extremely smooth because of the manufacturing tolerances between the polish rod and the oil well valve through which it reciprocates. The movement of the clamps and the necessity of securing them tightly against this smooth, lubricated surface of the polish rod in order to bear the entire weight of the rod string inevitably causes scarring and deformation of the polish rod surface. This action in turn rapidly damages the oil well valve mechanism and its packing, requiring frequent replacement thereof. An additional problem with using such clamps to hold the weight of the rod string of the oil well pump is that the clamps may slip, allowing the polish rod to fall into the oil well valve mechanism, causing both damage to the oil well valve mechanism and a substantial safety problem for servicing personnel.
Canadian Pat. No. 900,843 of Lodynski issued May 23, 1972, of general background interest, describes and illustrates an hydraulic cylinder apparatus which is attached to the polish rod of an oil well pump to permit controlled movement of that rod and assist in setting the suspension means of a deep well pump installation during operation. Canadian Pat. No. 530,257 describes and illustrates a polish rod clamp and Canadian Pat. No. 995,131 describes and illustrates a cable device to remove parts from a polish rod.
It is an object of the present invention to provide a device which may be used in servicing such an oil well pump which will avoid the requirement of undoing and relocating clamps on the polish rod to permit servicing to take place.